Cylindrical fuses of the type having an insulative body made of a material such as glass or a ceramic have been used for many years, particularly in automotive applications. Such fuses include a fusible link retained in the body or sleeve and connected to metallic end cups held at the ends of the sleeve. Two types of holders are generally used for such fuses. In the insertion type holder, two spaced pairs of terminal spring arms are provided with the pairs being spaced for alignment with the fuse end cups. The fuse is inserted by downward movement, causing the resilient arms to deflect until the fuse is fully received by the holder. In the in-line type holder, two plastic caps are provided with a terminal held in each cap and the conductor connected to each terminal extending through the end wall of the cap. The fuse is, for example, placed in one plastic cap and the other cap is moved longitudinally toward the one cap until the caps engage. The plastic caps may be provided with interlocking arms so that after the caps engage they can be twisted causing the arms to lock the caps thereby encapsulating the fuse. These in-line holders typically include a spring located inside one of the plastic caps for urging the terminals against the end cups of the fuse.
These prior art fuse holders can permit the entrance of moisture. This could result in corrosion of the metallic fuse end cups, the terminals for engaging the end cups and/or the spring. Furthermore, in an extreme situation the moisture could result in current shunting or bypassing the fuse thus defeating the purpose of the fuse and creating a potential safety hazard.
U.S. Pat. No. 3,778,741 to Schmidt, Jr. shows an in-line fuse holder including a pair of plastic caps with locking fingers permitting the caps to be joined by twisting. One cap holds a spring which bears against the inner surface of the end of the cap. U.S. Pat. No. 3,551,869 to Robinson is directed to a fuse holder including a pair of caps with one cap having an annular nose sized for reception in a bore in the other cap.
U.S. Pat. No. 3,301,979 to Fister discloses an O-ring which is compressed between components of a fuse holder against the inside surface of an outer wall. Operation of the O-ring is discussed in Col. 4, 11. 22-47. U.S. Pat. No. 3,321,733 to Thomas shows O-rings used for insulation in a high voltage connector to define a longer creepage path thereby eliminating corona discharge. U.S. Pat. No. 2,666,805 to Smith and U.S. Pat. No. 2,841,635 to Witzell et al. are directed to leakproof terminals and connections therefor.